Gas burner

ABSTRACT

1,117,749. Gas burners. JOH VAILLANT K.G. 22 Nov., 1965 [18 Dec., 1964; 31 Dec., 1964], No. 49442/65. Heading F4T. The outlet of a mixing chamber 5 is closed by a strip insert 6 having transverse discharge slots 7 and having its ends, or its longitudinal edges, Figs. 5, 6, not shown, bent into U-shape to form pressure reducing chambers, 9, 19 beneath the end discharge slots 7&lt;SP&gt;1&lt;/SP&gt;, or beneath the ends of all the discharge slots (Figs. 5, 6). Part of the mixture enters the pressure reducing chambers 9 through holes (10) in the ends of the strip 6 or through a gap (11) between the end of the insert and the main part thereof and the mixture discharges through the end slots 7&lt;SP&gt;1&lt;/SP&gt; at reduced rate of flow to provide adhering flames which continuously ignite the flames at adjacent slots.

Jan. 2, 1968 G. HEIN ET L 3,361,367

GAS BURNER Filed Oct. 21, 1965 }/2a ,1 I 21 Xx 76 7 2 21 27 19' 19 I 16' 16 i Fig. 5 Fig. 6

'F i g. 7

- INVENTORS 1 92L"; am; 4 14d Twfl BY M I United States Patent 3,361,367 GAS BURNER Georg Hein, Huckeswagen, and Erich Tropp, Remscheid,

Germany, assignors to Job. Vaillant KG, Remscheid, Germany Filed Oct. 21, 1965, Ser. No. 499,326 Claims priority, application Germany, Dec. 18, 1964,

V 27,390; Dec. 31, 1964, V 27,481

4 Claims. (Cl. 239553) ABSTRACT OF THE DISCLOSURE A gas burner is provided which includes a housing having an open top and forming a mixing chamber into which a combustible gas-air mixture is introduced under pressure. A burner insert is mounted across the open top of the housing. The insert has a plurality of openings through which the mixture flows for combustion above the insert. The insert is formed of sheet metal and has at least one side bent underneath to form a hollow tube along and under that side. The tube communicates with a part of at least one of said openings in the insert. The tube also defines a limited access entrance extending between the interior of the tube and the mixing chamber to permit the gas-air mixture to enter the tube while maintaining the pressure of the mixture in the tube less than the pressure in the chamber. The tube is otherwise closed whereby the gas-air mixture at said part of the burner opening will be at a pressure below that at the other burner openings to produce a more stable flame at that point.

The present invention relates to a gas burner comprising a mixing chamber from which the gas-air mixture discharges through a plurality of gas outlet openings.

It is the object of the present invention to provide a gas burner in which gases of different quality may be burnt.

In particular, it is the object of the invention to provide a gas burner wherein, when burning different gases of different ignition velocities, lifting of the flame is positively prevented.

It is a further object of the invention to provide a gas burner wherein for gases of diflerent properties a flashing back of the flame is positively prevented and a uniform and complete combustion ensured.

It is a further object of the invention to readily manufacture a burner of the type indicated in a simple manner.

In gas burners of the type indicated it is known to form adhering flames effecting a continuous ignition bridging of the burner if the regular burner flames lift off the burner at a flowout rate too high in proportion to the ignition velocity of the gas.

The adhering flames are supplied in known manner by a gas-air mixture at an artificially reduced flowout rate. Various possibilities of how to retard the portion of the outflowing gas mixture intended for supplying the adhering flames are known. One way is to provide pressure release chambers communicating with the mixing chamber with gas outlet openings at which adhering flames are produced. In such case the adhering flames are not supplied directly from the mixing chamber, but indirectly from the pressure release chambers from which a portion of the gas mixture is discharged at substantially reduced rate of flow.

It is the object of the present invention in a gas burner made of sheet metal parts to provide such pressure release chambers intended for supplying adhering flames in a simple manner at low manufacturing expense, without additional parts having to be attached and connected with the burner parts. The invention resides in the fact 3,361,357 Patented Jan. 2, 1968 that the pressure release chambers are bounded by U- shaped, downwardly rounded off edge portions, bent of a burner insert formed with the gas outlet openings and closing off the mixing chamber. The invention may be expediently realized by having the lengthwise edge portions of a strip type burner insert provided with transverse gaS outlet slots bent downwardly so as to be U-shaped, such that lengthwise extending pressure release chambers are produced beneath the ends of the gas outlet slots. With such a design of the burner insert no additional gas outlet openings need be provided for the adhering flames. Instead the adhering flames burn at the ends of the gas outlet slots provided for the burner flames in close vicinity to the burner flame.

Provision may, however, also be made that the short edge portions of a strip type burner insert, provided with gas outlet openings, are bent downwardly so as to be U-shaped such that pressure release chambers will be produced at the ends of the burner insert beneath at least one gas outlet opening. In this manner, adhering flames will be obtained at the ends of the burner insert. This is of particular significance for gas burners with a substantially horizontally arranged V-shaped mixing chamber. It has been shown that with such configuration of the mixing chamber the flames burning at the end areas of the burner insert show particular tendency to lift. Obviously, this is due to pressure baiflng effects and nonuniform pressure distribution in such a mixing chamber. Thus, it is advantageous to provide adhering flames at the very end areas of the burner insert in the manner as described.

In order to be able to burn different gases of different ignition velocities in flash-back-proof manner with such a gas burner, it is necessary to provide relatively narrow gas outlet slots in the burner mouthpiece which slots have previously been spaced from each other by equal distances. However, since the pressure conditions which prevail in a horizontal mixing chamber beneath the gas outlet slots are by no means homogeneous, the gas-air mixture discharges from the individual slots at different rates of flow so that there will be different flame pictures and different conditions for the secondary air intake. If the gas supply to the mixing chamber and the primary air intake are adapted such that the combustible mixture discharges from the gas outlet slots being next adjacent to the gas nozzle in direction of the flow at a suflicient rate of flow, the flowout rate of the mixture will be reduced at the further gas outlet slotswith the exception of a few gas outlet slots located at the very end of the burner, a fact to be neglected at present. This is due to the flow conditions in the horizontal mixing chamber. Surprisingly enough, it has shown that the flames become longer and more unstable at the gas outlet slots at which the mixture discharges at a reduced rate of flow, and also exhibit a slight inclination in the central area of the burner, while at the next adjacent gas outlet slots there will be produced relatively short taut flames.

Therefore, the flame picture of such gas burner is nonuniform and combustion is incomplete. This may therefore result in undesired formation of CO and in local overheating of a fin block arranged above the burner, of a continuous-flow heater. It is the object of the present invention to improve on the nonuniform flame picture as described of such a gas burner.

According to the invention this object is attained, by the provision of spacings of the gas outlet slots in the burner mouthpiece that are extended with increasing distance from the gas inlet nozzle effecting the primary air intake. In doing so, it has been discovered that it is of importance to facilitate the secondary air intake, in which is insuflicient due to the reduced flowout rate of the mixture, which intake defines the nature of the flame. As the secondary air supply is improved by increased distances between the gas outlet slots, the longer unstable flames become shorter and tauter. With suitable dimensioning of the slot distances, a uniform flame picture can be obtained over the whole burner length. This result cannot be obtained by providing gas outlet openings of increasing size in well-known manner, apart from the fact that an enlargement of the gas outlet openings is prohibitory on account of the required safety against flashback.

A few embodiments of the invention are presented in the drawings and described as follows:

FIG. 1 is a diagrammatic illustration of a gas burner in elevational view.

FIG. 2 is a plan view thereof.

FIGS.'3 and 4 are sections of one end of the burner insert on an enlarged scale.

FIG. 5 is a cross-section through a burner insert of different embodied form, on an enlarged scale.

FIG. 6 is the respective plan view thereof.

FIG. 7 illustrates diagrammatically a modification of the burner of FIG. 1 with diiferent distancees of the gas outlet slots.

A manifold 1 formed with gas outlet nozzles has attached thereto in juxtaposed relationship several individual gas burners 3, only one of which being shown. Gas burner 3 comprises a housing formed by two burner cups 4, 4' made from pressed sheet metal, which housing defines a Vshaped mixing chamber 5, and has a strip type burner insert 6 closing off the top of the mixing chamber 5. The burner insert 6 is formed with numerous parallel gas outlet slots 7.

The ends 8, 8' of burner insert 6 are bent so as to be U-shaped and rounded off downwardly so that there will be two tubes, each of which forms a pressure reduction chamber 9, 9', below the last gas outlet slots 7' respectively. The reduction chamber 9, 9 communicate with the mixing chamber 5 either by punched out holes 10 (as in FIG. 3) or by a gap (as in FIG. 4) between the sheet metal edge and the bottom of the burner insert.

In the well known manner the gas flowing from nozzl 2 aspirates primary air into the mixing chamber 5 where the gas and air are mixed. The gas-air mixture discharges from mixing chamber 5 through the gas outlet slots 7.

'Gas discharge does, however, not take place uniformly since flow in the mixing chamber 5 causes a pressure bafliing effect both at the right and the left ends of the burner 3. Therefore, from the gas outlet slots 7 located in the end areas of burner insert 6 the gas mixture discharges at a slightly higher rate than from the outlet slots located in the central area so that the gas flames will more likely tend to liftin the end areas.

The 'gas mixture also enters the reduction chambers 9,9 wherein a pressure drop is caused by turbulence. Therefore, the gas mixture will discharge from the end outlet slots 7' at'an artificially reduced rate of flow. The reduced flow causes adhering flames at these locations which provide for continuous ignition for the gas flames which tend to lift from the adjacent inner gas release slots 7.

.IIl the embodiment as illustrated in FIGS. 5 and 6- the full length thereof. These chambers are arranged beneath the ends of the transversely extending gas outlet slots 17.

This structure results in a main flame 20 at each outlet slot 17 and both sides thereof smaller adhering flames 21, 21' supplied from the release chambers 19, 19.

It is, of course, possible to form adhering flames at one or both sides of each or only individual burner flames as well as provide them additionally at the ends of the burner insert.

The burner insert 6, 16 is made from corrosion-resistant sheet metal such as stainless sheet steel. It is supported by impressed beads 14 of the two burner cups 4, 4. The two cups are joined together as by a rabbet 13.

In the embodied form according to FIG. 7 the burner slots are spaced differently. The spacings increase from the right-hand side leftwardly. To accommodate the same number of gas outlet slots 7, in the right-hand portion of burner insert 6 these are moved together somewhat closer and increasingly spread apart leftwardly instead. The spacings of the gas outlet slots 7 are decisive for the secondary air intake are thus the greater, the less is the flowout rate of the gas mixture, thereby ensuring that all individual flames have suificient secondary air supply and the flame picture has the configuration as shown in FIG. 4. This will result in a uniform flame picture as illustrated at 22.

The invention is claimed as follows:

1. In a gas burner apparatus including a housing having an open top and forming a. mixing chamber into which a combustible gas-air mixture is introduced under pressure, with a burner insert across said open top and having a plurality of openings through which the mixture flows for combustion above the insert, the improvement 3 comprising: said insert being formed of sheet metal having at least one side thereof bent underneath to form a hollow tube along and under said side, said tube communicating with a part of at least one of said openings, said tube defining a limited access entrance extending between the interior of the tube and the chamber to permit said mixture to enter said tube while maintaining the pressure of the mixture in the tube less than the pressure in the chamber, said tube being otherwise closed whereby the gas-air mixture at saidpart of said open- 7 most nearly adjacent the point of introduction of said gas-air mixture being the closest together and those most remote from said point being spaced the farthest apart.

References Cited UNITED STATES PATENTS 1,451,072 4/1923 Hoffstetter 239-5513 FOREIGN PATENTS 1,189,225 12/1960 Germany.

M. HENSON woon, JR., Primary Examiner,

M. MAR, Assistant Examiner, V 

